This invention relates to an actuator system for shifting a control device that is pressure-loaded in the direction opposite the shift direction, said actuator system incorporating an actuator element capable of being axially moved in the shift direction within a system enclosure by a rotating spindle of an advance mechanism, which rotating spindle is slidingly connected to a rotating sleeve that is pivot-mounted in the system enclosure and surrounds the rotating spindle which latter, relative to a circular flange rigidly connected to the system enclosure, is locked in position in the direction opposite the direction of advance rotation of the rotating spindle by means of a volute spring which volute spring is associated with an emergency release unit for resetting the actuator element against the shift direction.
An actuator system of this type has been known in prior art, serving to actuate control devices such as valves, pressure regulators and other control mechanisms but employed most particularly in submarine oil and gas exploration and production equipment. Evidently, the actuator system can be employed equally well in comparable land-based, difficult-to-access or remote locales.